In order to control the idle speed of an internal combustion engine, it has been common to utilize various types of devices which function to form a stop for the throttle. Such devices have been commonly known as throttle kickers and are shown, for example, in U.S. Pat. Nos. 3,730,153, 3,760,785 and 4,056,082. The devices have been commonly electrically energized solenoids or vacuum actuated diaphragm devices or combinations of the two. In such devices combining a solenoid and a vacuum actuated device, the devices may not have been capable of an anti-dieseling function because when the solenoid is de-energized, vacuum continues to maintain the stem of the device so that the stem cannot return to its original position unless provision is made for relieving the vacuum quickly.
Another problem of the combined type of throttle positioning device has been that the solenoid must have sufficient force to overcome the hysteresis of the vacuum device and the friction of the seals.
Among the objectives of the present invention are to provide a throttle positioning device which is capable of positioning the throttle stop that, in turn, controls the throttle position and which utilized a solenoid and a vacuum device wherein the stem that functions as a throttle stop will return to its most retracted position when the solenoid is deenergized; which will preferably provide at least four positions of the stem; wherein the solenoid will function to move the stem without independently moving the vacuum actuated device; and wherein the position of the stem can be adjusted to set the normal idle RPM.
In accordance with the invention, the throttle positioning device comprises a housing, a diaphragm in the housing dividing the housing into first and second chambers. The housing has an opening extending to the first chamber for connection to vacuum. A solenoid is associated with the housing and has a plunger slideable upon energization of the solenoid. The plunger is yieldingly urged by a light spring against a solenoid stop connected to the diaphragm such that the stop is movable with the diaphragm. A stem is adapted to be connected to the plunger and extends through the movable stop to the exterior of the housing to define a movable throttle stop. The throttle lever, attached to the throttle shaft of the carburetor, yieldingly urges the throttle stop to a retracted position against the lighter spring force of the solenoid plunger. The diaphragm is yieldingly urged to move the movable solenoid stop toward the solenoid. When the solenoid is energized and vacuum is not being supplied to the first chamber, the stem is in a first position, and when said solenoid is energized and vacuum is supplied to the first chamber, said stem is in a second position. In another form, the throttle positioning device includes a wall in the housing cooperating with the first diaphragm to form the second chamber, and a second diaphragm cooperating with the wall to define third and fourth chambers. The housing has an opening for connection to vacuum. The first and second diaphragms are movable independently of one another, such that when the solenoid is energized and vacuum is applied to the second opening, the second diaphragm moves the first diaphragm to move the magnetic stop so that the stem is moved by the solenoid plunger to a fourth position.